As regards the thickening of the edge near the articulation axis towards the two articulation vertices, it may be noted that European patent Nos. 0023797 and 0113681 (see, in particular, FIG. 8 of both the patents in question) show bi-leaflet valve obturators of constant thickness, the end articulation regions of which are slightly thicker than the obturator which is nevertheless of strictly constant thickness. The obturators described in the prior documents thus lack the progressive increase in thickness from the centre towards the vertices which, in the obturator according to the invention, is present in addition to or instead of the progressive reduction in the thickness of the obturator between its two opposite edges.
The invention will now be described, purely by way of non-limiting example, with reference to the appended drawings, in which: